Position sensing apparatus

ABSTRACT

A paper stacker for stacking a continuous paper web in fan-fold form from a printer is disclosed. Rollers having radially projecting resilient fingers engage both folded edges of the web as it is stacked. The rollers are each driven by a motor through a gear secured to the roller shaft. The motor is carried on a plate pivotted about the shaft the plate being held against rotation about the shaft by a spring. When the stack height brings the upper surface of the stack sufficiently close to the rollers the load on the rollers is sufficiently great to cause rotation of the plate against the tension of the spring, thereby making an electrical contact to actuate mechanism for raising the rollers.

United States Patent 1 1 Sturman et al. I 1 Nov. 6, 1973 [54] POSITIONSENSING APPARATUS 3,083,010 3/l963 Salmon et al. 270/73 l,lO9,296 91914L 's [751 Inventors: Geoffrey Wilfred 3,640,521 2/1972 HZYIL 270/61 FFrederick Sinfield, both of Letchworth, g Primary Examiner-Robert w.Michell [73] Assignee: International Computers Limited, Assistant 'f THelm London, England Attorney-Kath Misegades and George R. Douglas, Jr.221 Filed Dec. 10, 1970 [57] ABSTRACT [21 Appl. No.: 96,798 A paperstacker for stacking a continuous paper web in fan-fold form from aprinter is disclosed. Rollers having radially projecting resilientfingers engage both folded [30] Forelgn Applicaumi P nomy Data edges ofthe web as it is stacked. The rollers are each Dec. 16, 1969 GreatBr1ta1n 6l,l53/69 driven by a motor through a gear Secured to the rollershaft. The motor is carried on a plate pivotted about [52] [1.8. CI270/79, 73/432 R, 340/280 the Shaft the plate being held againstrotation about the [51] 'llil. Cl 365]] 45/20 Shaft by a spring w thestack height brings the [58] Fleld of Search 270/79, 61-62, upperSurface of the Stack sufficiently close to the 270/82 73; 340/259;271/8, 63; ers'the load on the rollers is sufficiently great to cause83/83 rotation of the plate against the tension of the spring, 0 therebymaking an electricalrcontact to actuate mecha- [56] References and nismfor raising the rollers.

UNITED STATES PATENTS 4 Claims, 2 Drawlng Figures 3,5l0,899 5/1970Vollenweider et al 15/DIG. 2 3,178,172 4/1965 Lettan 270/79 POSITIONSENSING APPARATUS BACKGROUND OF THE INVENTION The present inventionrelates to position sensing apparatus and particularly, but notexclusively, to apparatus for sensing the position of one surface of astack formed, for example, by stacking apparatus.

SUMMARY OF THE INVENTION According to one aspect of the invention aposition sensing device for detecting the position of a moveable surfaceincluded at least one member positioned on a rotatable shaft, the shaftbeing positioned transversely to and spaced away from the surface in thedirection of movement of the surface; drive means supported on amounting rotatable about the shaft for applying rotational drive to theshaft in one sense; means for applying a predetermined force to resistrotary movement of the mounting about the shaft in the opposite senseand means for detecting rotary movement of the mounting about the shaftin said opposite sense against the applied force, whereby movement ofthe surface towards the shaft causes frictional engagement of saidmember with the surface at a predetermined spacing between the surfaceand the shaft sufficient to overcome said force and produce said rotarymovement of the mounting.

According to another aspect of the invention stacking apparatus forstacking a continuous web in fan-fold form includes a support surfacefor a fan-fold stack; a support member carrying a position sensingdevice; means operable in response to detection of the rotary movementof the mounting to produce relative. motion between the support memberand the support surface to increase the spacing therebetween and therebymaintain the support member at a substantially constant spacing fromthe' face of the stack.

BRIEF DESCRIPTION'OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENTReferring now to FIG. 1, a stacking apparatus is arranged to form apre-folded paper web 1 into a compact stack 2. The stacking arrangementshown in the Figure is particularly suitable for handling a continuouspaper web from, for example, the printing mechanism ofa data processingequipment. Typically, such equip ment uses continuous stationery derivedfrom a stack in which the web is folded back and forth in a zig-zagconfiguration and it is required to reform the web into a similar stackafter it has been printed.

The stacking apparatus is supported on a hollow base 3, the top 4 of thebase 3 forming a stacking platform. A vertical arm 5 is provided at eachside of the base 3.

The arms are spaced apart at their upper ends by a pair" of rods 13. Aframework 6 is mounted between a pair of sliders 7, each slider beingarranged to move vertically along one of the arms 5. An endless chain38'is carried over sprockets 39 and 40, respectively mounted at theupper and lower ends of each of the arms 5, and

the sliders 7 are secured to the chains 38 by means of connecting pieces41. The upper sprockets 39 are idlers and are each supported on a stud42 in the arms 5. The lower sprockets 40 are mounted on a shaft 42passing cross the interior of the base 3. The shaft 43 is coupled in aconventional manner by gearing (not shown) through anelectrically-actuated clutch (not shown) to a drive motor (not shown)within the base 3. It will'be realised, therefore that by the selectiveoperation of the clutch theshaft 43 may be driven to move the chain 38and raise the entire framework 6. It will also be appreciated thatreversal of the direction of rotation of the motor within the base 3will cause the entire framework 6 to be lowered if the clutch isenergised.

The framework 6 consists of a pair of side members 8 secured together bybars 9 passing across the width of the framework 6. A pair of plates 10are supported by the side members 8 between the arms 5. The end plates10 house bearings (not shown) for transverse shafts 11 which carry feedrollers 12.

The shafts 11 are driven ,by conventional gearing (not shown) from asplined shaft 44 arranged vertically in bearings of which only one, 46,is shown, carried by one of the arms 5. The splined shaft 44 is drivenby bevel gearing 45 through a further clutch and motor combination (notshown) within the hollow base 3.

At the left-hand end, as shown in FIG], the framework 6 supports a shaft14. The shaft 14 passes across the framework and is journalled into theside members 8. Finger-rolls 15 are spaced apart along the shaft 14.Parallel with the shaft 14 a bar 49 is also supported between the sidemembers 8, and the bar 49 carries a number of stop members 50 andflexible strips 51, the members 50 and strips 51 being spaced apartalong the bar- 49 to lie between the finger rolls 15. FIG. 2 shows thearrangement of the finger rolls 15, the members 50 and the strips 51 ingreater detail.

As indicated in FIG. 2,- each finger roll consists of a hub 16 securedto the shaft'l4. The hub 16 is of resilient material and has a number ofequally-spaced fingers l7 projecting outwards from it. The fingers I7taper from the hub towards their free ends. The bar 49 is positioned sothat it is clear to the fingers 17 of the rolls [5. Intermediateadjacent rolls l5 stop members 50 are secured to the bar 49, each stopmember having a downwardly projecting portion to act as a stack-edgealignment member, and an upper end bentinward's to form an anchoringpoint to which is secured one end of a flexible strip 51'. The strip 51,which is preferably made of spring steel, is curved first upwards, thendownwards to enclose the shaft 14, the free end of the strip 51 beingpassed through a hole 52 provided for the purpose in the stop member 50.The free end of the strip 51 is bent sharply-downwards to contact theout- .ward'face of the member 50, being located in this position by thetension induced into the strip SI by its curvature.

The side members 8 (FIG. 1) have channels 18 formed'in their outwardfaces towards those ends of the members 8 remote from the shaft 14.Extension pieces pieces 19 are held in position in the channels 18 bymeans of a thumbscrew clamp 21 which project through slots in therespective side members 8 so that the extent of the projection of thepieces 19 from the ends of the side members 8 may be adjusted.

The right-hand ends, as shown in FIG. 1, of the extension pieces 19,carry a finger-roll and stop member arrangement similar to thatdescribed above at the lefthand side of the framework 6. A shaft 22,journalled into the extension pieces 19 carries finger rolls 23. A bar53 carries right-hand stop members 54 and flexible strips 55 carried bythe members 54 passes round the shaft22.

The finger roll shafts l4 and 22 are each associated with an independentdrive unit 24. The drive units 24 are similar, that associated with theshaft 22 being shown with greater clarity in the figure and beingdescribed in detail. This drive unit 24 includes a plate 25 which ispivoted on the shaft 22. A shaft driving gear 26 is secured to the shaft22 so that the plate 25 is sandwiched between the gear 26 and the outerface of one of the extension pieces 19. The plate 25 carries a stud 27on which is mounted an idler gear 28 meshing with the driving gear 26. Amotor 29 having a drive shaft 30 is carried on the plate 25 and a gearwheel 31 meshing with the idler gear 28 is provided on the motor shaft.Thus, the idler gear 28 merely serves to couple the drive from the motor29 to the driving gear 26, and so to the shaft 22, the motor beingconnected so that, when engaged, it drives the gear 26 in ananticlockwise direction as shown in the drawing.

A support block 47 is secured to the extension piece 19 adjacent thedrive unit 24 and carries at one end a thumbscrew 32. The end of thethumbscrew 32 projects from the block 47 towards the plate 25 and atension spring 33 is used to couple the screw 32 to the plate 25 toresist rotation of the plate 25 in a clockwise direction as shown in thedrawing. The plate 25 also has a lug 34 turned at right angles to theplane of the plate 25. An adjusting screw 35 is threaded through the lug34 and the end of the screw 35 projects beyond the plate 25 in such adirection as to lead that edge of the plate 25 if the plate rotatesabout the shaft in a clockwise direction as shown on the drawing. Amicroswitch 36 is supported on a mounting block 48 so that it has anactuating lever 37 resting against the projecting end of the screw 35.

An electrical circuit, (not shown) is provided to control the operationof the motors of the apparatus and this circuit has the followingfeatures: The motor (not shown) which drives the chain 38 is controlledby a switch which is normally closed when the apparatus is in use, sothat energisation of the clutch (not shown) referred to in connectionwith the chain-drive transmits the motor drive to the chain 38. Thisdrive motor is normally running in such a direction as to move the chain38 to raise the framework 6. In addition, further switches are providedto reverse the direction of the motor drive and to energise the clutchunder manual control, so that the framework 6 may be moved upwards ordownwards under manual control in order that it may be positioned at arequired height. The microswitch 36 is connected into the energisationcircuit of the clutch so that the clutch is energised whenever themicroswitch 36 is operated. Because the normal direction of the motordrive is such that the framework 6 is raised, it will be seen thatoperation of the microswitch 36 under these normal operating conditionscauses the framework 6 to rise for as long as the microswitch remainsoperated. The switch referred to above initially energising the chaindrive motor is also used to energise the motor (not shown) associatedwith the drive to the splined shaft 44, so that under normal operationalconditions the feed rollers 12 are continuously rotating.

In operation, the end of a paper web 1 to be stacked is passed downwardsbetween the rods 13 and then through the feed rolls 12. The rolls 12 arearranged lightly to grip the web and the direction of rotation of therolls 12 is such as to feed the web downwards. The rolls 12 preferablyeach have a resilient periphery and are arranged to skid on the surfaceof the web 1 so that the web 1 is not damaged by the rolls 12 in theevent that the external supply of the web 1 is at a rate less than thestacker can handle. A refinement of operation that may be employed is toarrange the circuit to control the drive to the splined shaft 44 in sucha way that the shaft 44 is driven only while the web 1 is being supplied.to the stacker.

The web-end passed downward through the feed rolls 12 is laid on theupper surface 4 of the base 3 so that the preformed folds in the web 1enable the incoming web to take up its originally folded form. Theframework 6 is then lowered by manual operation until the tips of thefingers 17, of the finger rolls,15 and 23 gently stroke the folds of thestack 2 as it is formed, the position of the extension pieces 19 beingadjusted with respect to the framework 6 so that the fingers of therolls l5 and 23 act on the stack near its folded edges.

As the web 1 is fed into the stacks the pre-foldcd creases allow it toassume the original zig-zag formation with the result that thepre-formed creases are impelled towards one or other of the stop members50 or 54 alternately. As a crease approaches the appropriate stopmember, it contacts the curved inward-facing surface of the associatedflexible strip 51 or 55 respectively. The action of the strip 51 or 54is to absorb the kinetic energy of the approaching crease and the stopmember 50 or .54 then acts as an aligning stop to dress the incoming web1 into the stack 2. The finger rolls 15 and 23 aid the formation of thestack by lightly dressing the incoming web downwards and towards therespective stop members 50 and 54. At this point in the operation, thecircuitry associated with control of the height of the framework 6 isput into normal operation.

As the web 1 continues to feed into the stack 2, the stack graduallyincreases in height. As the stack 2 grows higher, the resilient fingersof the rolls l5 and 23 are flexed more and more, with the result that aprogressive increase in resistance to the rotation of the rolls 15 and23 is built up. For the sake of clarity the operation of the drive unit24 associated with the finger rolls 23 will be considered in detail.

It will be recalled that the finger rolls 23 are driven by the motor 29through gears 31, 28 and 26 and that the gear 26 rotates in ananticlockwise direction as shown. It will also be remembered that theplate 25 is pivoted about the finger roll shaft 22 but is maintainedagainst turning in a clockwise direction by the force exerted by thespring 33. Hence, as the resistance to rotation of the finger rolls 23,and, in consequence to rotation of the gear 26, is built up the torqueapplied to turn the gear 26 results in the gear 28 moving in a clockwisedirection round the periphery of the gear 26, thus pivoting the plate 25clockwise about the shaft 22 against the force exerted by the spring 33.This movement of the plate 25 carries the screw 35 towards themicroswitch 36, flexing the levers 37, until the microswitch 36 isactuated. It will be recalled that actuation of the microswitch 36causes the framework 6 to be raised, and this upward movement of theframework 6 opens the gap between the top surface of the stack 2 and thefinger rolls 23 so that resistance to rotation of the rolls 2-3 islessened. The plate 25 now restores under the influence of the spring33, and the screw 35 moves away from microswitch 36, which is thusallowed to restore to its initial state. It will be seen, therefore,that the right-hand drive unit 24, allows the framework 6 to be raisedto follow the increasing height of the right hand edge of the stack 2,as shown. The left hand drive unit 24 operates in the same way withrespect to the lefthand edge of the stack 2.

It will be realised that the provision of two drive units 25 permits thefinger rolls and 23 at opposite edges of the stack to act together toalign the edges of the stack by causing successive layers to be locatedon the stack according to the pre-formed folds. It will be understood,however, that in the arrangement so far described, where the entireframework 6 is rigidly mounted on the slides 7, it is only necessary tosense the height of the stack by means of one drive unit 24, so thatunder these conditions satisfactory stacking may be obtained byproviding a moveable plate and a microswitch 36 in only one of thedriving units 24.

It has been found, however, that, particularly for high feeding rates ofthe web 1, the provision of microswitches 36 in both drive units 24allows greater operational tolerance in the mechanical response of theunits 24, In particular, the tolerance of the apparatus to themechanical restoration characteristics of the plates 25 is improved. Itis also found that under some conditions of operation it is desirable toarrange that the microswitches 36 are mounted on the opposite sides ofthe plates 25 to that shown in the drawing, the lugs 34 and adjustingscrews also being positioned on the opposite sides of the plates 25. Inthis way the plates 25 tend to move away from instead of towards themicroswitches as the stack height increases. Thus a rapid build up ofthe stack with a consequent violent swing of the plates 25 can takeplace without risk of damage to the microswitches 36 by impact from theplates 25. It will be realised that with this arrangement themicroswitches are actuated by the plates 25 in their normal positionsand are de-actuated as the plates 25 are moved in response to increasingstack height, the microswitches being arranged to make an electricalcircuit upon de-actuation.

It will also be readily seen that the height of the folded edges of thestack 2 increases at a greater rate than does the height of the centreof the stack 2. It is for this reason, for example, that it is preferredto make the centre of the upper surface 4 of the base 3 higher 7 thanthose edges of the surface 4 on which the folded edges of the stack 2rest, as indicated in the drawing. if, instead of rigidly mounting theframework 6, in the slides 7, the framework 6 is pivotally mounted and aheight adjusting structure including, for example, a separate chain 38for each end of the framework 6 is provided, then the use of theposition sensing arrangement in the drive units 24 associated with bothsets of finger rolls l5 and 23 would allow the height of the ends of theframework 6 to be separately controlled. Under these conditions, thefinger rolls 15 and 23 respectively associated with the opposite edgesof the stack 2 may each be maintained in an optimum position withrespect to the particular associated edge.

It will be seen, therefore, that the drive units 24 in association withthe finger rolls 15 or 23 form devices both for sensing the position ofthe upper surface of the stack 2 with reference to the ends of theframework 6 and for controlling the height of the framework 6 tomaintain the spacing between the framework 6 and the upper stack surfacewithin a predetermined tolerance, dependent upon the resilience of thefingers of the finger rolls and the adjustment of the force exerted bythe springs, such as 33, and upon the adjustment of the screws 35.

The movement of the plate 25 is primarily controlled by the resistanceto rotation offered to the finger roll shaft 22, and it will be realisedthat rolls each having, for example, a flexible'periphery could besubstituted for the finger rolls shown, provided that these rolls areable to engage the upper surface of the stack 2 with sufficientfrictional resistance to motion to produce movement of the plate 25without at the same time damaging the surface of the stack 2.

It is also to be understood that conversely, the use of the finger rollsis not limited to the actuation of the position sensingdevice within thedrive unit 24. As has been pointed out, where only one position sensingdevice is used, a second set of finger rolls is used to aid in formingthe stack. Moreover, finger rolls may also be used in opposition toreplace th resilient surfaced rolls 12 in feeding the web into thestacking arrangement.

The use of finger rolls in this position may actually aid the formationof the stack by allowing the pre-folded creases in the web to passthrough the feeding station without any contact from feeding rolls whichwould tend to flatten the creases.

It will be recalled that the base 3 is described as housing separatemotors to drive the splined shaft 44 and the chain sprocket 40respectively. It will be understood, however, that a single motor may beused as the prime mover for both purposes, the drive from the motorbeing communicated by conventional gearing and electrically controlledclutches. For example, a first gear train may be used to drive thesplined shaft 44, and a clutch in this drive chain may be interlocked bymeans of an electrical connection so that the shaft 44 is driven onlywhile the web 1 is being supplied to r the stacking arrangement. If, forexample, the stacker is employed at the output of a printing apparatus,an electrical signal may be transmitted to actuate the splined shaft 44clutch whenever a spacing or paper feeding operation'is initiated by theprinting apparatus. The facility for manual control of the lowering ofthe framework 6 may be provided by having a dual drive,

effective selectively to produce raising or lowering respectively of theframework-6. If each drive is separately clutchable, then a conventionalelectrical interlock may be used to ensure that while signals from themicroswitch or switches 36 are effective, to produce upward movement ofthe framework, the upward" clutch cannot be actuated while the downward"clutch is being signalled under manual control, and indeed to providesuch a manual override for movement of the framework 6 in eitherdirection.

We claim: i

1. Apparatus for stacking a precreased fan-fold web, including a basemember; a framework mounted for movement towards and away from the basemember;

web feeding means mounted on the framework and operable to feed the webwhen in an unfolded condition towards the base member such that a stackof refolded web is formed on the base member the stack having opposededges formed by the precreased folds in the web; a shaft mounted on theframework; a stack edge contacting roll mounted on the shaft, the rollbeing positioned adjacent to one of said edges so that it comes intocontact with the web being fed to assist in the refolding of the webonto the stack as the depth of the stack increases; means operable torotate the roll; detecting means operable in response to a predeterminedincrease in the resistance to rotating of the roll consequent upon itscontact with the increasing depth of the stack; and driving meansoperable in response to operation of the detecting means to move theframework away from the base member to allow the edge contacting roll toaccomodate to the increasing depth of the stack 2. Apparatus as claimedin claim 1 in which the detecting means includes a plate pivotallymounted on said shaft; spring means resiliently urging the plate towardspivotting in one direction about the shaft; electrical switching meanspositioned for operation by the plate pivotting in a direction oppositesaid one direction and in'which the said driving means is mounted on theplate. a

3. Apparatus as claimed in claim 2 in which the roll has a plurality .ofradially arranged fingers of resilient material.

4. Apparatus as claimed in claim 1 in which the base member with whichthe stack is in contact is so shaped as to provide first and secondouter portions for contacting and supporting the opposed folded edges ofthe stack, and a third portion intermediate the first and secondportions raised relative to the first and second por-

1. Apparatus for stacking a precreased fan-fold web, including a basemember; a framework mounted for movement towards and away from the basemember; web feeding means mounted on the framework and operable to feedthe web when in an unfolded condition towards the base member such thata stack of refolded web is formed on the base member the stack havingopposed edges formed by the precreased folds in the web; a shaft mountedon the framework; a stack edge contacting roll mounted on the shaft, theroll being positioned adjacent to one of said edges so that it comesinto contact with the web being fed to assist in the refolding of theweb onto the stack as the depth of the stack increases; means operableto rotate the roll; detecting means operable in response to apredetermined increase in the resistance to rotating of the rollconsequent upon its contact with the increasing depth of the stack; anddriving means operable in response to operation of the detecting meansto move the framework away from the base member to allow the edgecontacting roll to accomodate to the increasing depth of the stack 2.Apparatus as claimed in claim 1 in which the detecting means includes aplate pivotally mounted on said shaft; spring means resiliently urgingthe plate towards pivotting in one direction about the shaft; electricalswitching means positioned for operation by the plate pivotting in adirection opposite said one direction and in which the said drivingmeans is mounted on the plate.
 3. Apparatus as claimed in claim 2 inwhich the roll has a plurality of radially arranged fingers of resilientmaterial.
 4. Apparatus as claimed in claim 1 in which the base memberwith which the stack is in contact is so shaped as to provide first andsecond outer portions for contacting and supporting the opposed foldededges of the stack, and a third portion intermediate the first andsecond portions raised relative to the first and second portions forcontacting the central portion of tHe stack.